/*
 * Entry.java July 2007
 *
 * Copyright (C) 2007, Niall Gallagher <niallg@users.sf.net>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
 * implied. See the License for the specific language governing
 * permissions and limitations under the License.
 */

package wx.xml.simpleframework.xml.core;

import wx.xml.simpleframework.xml.ElementMap;
import wx.xml.simpleframework.xml.strategy.Type;

/**
 * The <code>Entry</code> object is used to provide configuration for
 * the serialization and deserialization of a map. Values taken from
 * the <code>ElementMap</code> annotation provide a means to specify
 * how to read and write the map as an XML element. Key and value
 * objects can be written as composite or primitive values. Primitive
 * key values can be written as attributes of the resulting entry
 * and value objects can be written inline if desired.
 *
 * @author Niall Gallagher
 */
class Entry {

    /**
     * Provides the default name for entry XML elements of the map.
     */
    private static final String DEFAULT_NAME = "entry";

    /**
     * Represents the annotation that the map object is labeled with.
     */
    private ElementMap label;

    /**
     * Provides the point of contact in the object to the map.
     */
    private Contact contact;

    /**
     * Provides the class XML schema used for the value objects.
     */
    private Class valueType;

    /**
     * Provides the class XML schema used for the key objects.
     */
    private Class keyType;

    /**
     * Specifies the name of the XML entry element used by the map.
     */
    private String entry;

    /**
     * Specifies the name of the XML value element used by the map.
     */
    private String value;

    /**
     * Specifies the name of the XML key node used by the map.
     */
    private String key;

    /**
     * Determines whether the key object is written as an attribute.
     */
    private boolean attribute;

    /**
     * Constructor for the <code>Entry</code> object. This takes the
     * element map annotation that provides configuration as to how
     * the map is serialized and deserialized from the XML document.
     * The entry object provides a convenient means to access the XML
     * schema configuration using defaults where necessary.
     *
     * @param contact this is the point of contact to the map object
     * @param label   the annotation the map method or field uses
     */
    public Entry(Contact contact, ElementMap label) {
        this.attribute = label.attribute();
        this.entry = label.entry();
        this.value = label.value();
        this.key = label.key();
        this.contact = contact;
        this.label = label;
    }

    /**
     * This represents the field or method that has been annotated as
     * a map. This can be used to acquire information on the field or
     * method. Also, as a means of reporting errors this can be used.
     *
     * @return this returns the contact associated with the map
     */
    public Contact getContact() {
        return contact;
    }

    /**
     * Represents whether the key value is to be an attribute or an
     * element. This allows the key to be embedded within the entry
     * XML element allowing for a more compact representation. Only
     * primitive key objects can be represented as an attribute. For
     * example a <code>java.util.Date</code> or a string could be
     * represented as an attribute key for the generated XML.
     *
     * @return true if the key is to be inlined as an attribute
     */
    public boolean isAttribute() {
        return attribute;
    }

    /**
     * Represents whether the value is to be written as an inline text
     * value within the element. This is only possible if the key has
     * been specified as an attribute. Also, the value can only be
     * inline if there is no wrapping value XML element specified.
     *
     * @return this returns true if the value can be written inline
     */
    public boolean isInline() throws Exception {
        return isAttribute();
    }

    /**
     * This is used to get the key converter for the entry. This knows
     * whether the key type is a primitive or composite object and will
     * provide the appropriate converter implementation. This allows
     * the root composite map converter to concern itself with only the
     * details of the surrounding entry object.
     *
     * @param context this is the root context for the serialization
     * @return returns the converter used for serializing the key
     */
    public Converter getKey(Context context) throws Exception {
        Type type = getKeyType();

        if (context.isPrimitive(type)) {
            return new PrimitiveKey(context, this, type);
        }
        return new CompositeKey(context, this, type);
    }

    /**
     * This is used to get the value converter for the entry. This knows
     * whether the value type is a primitive or composite object and will
     * provide the appropriate converter implementation. This allows
     * the root composite map converter to concern itself with only the
     * details of the surrounding entry object.
     *
     * @param context this is the root context for the serialization
     * @return returns the converter used for serializing the value
     */
    public Converter getValue(Context context) throws Exception {
        Type type = getValueType();

        if (context.isPrimitive(type)) {
            return new PrimitiveValue(context, this, type);
        }
        return new CompositeValue(context, this, type);
    }

    /**
     * This is used to acquire the dependent key for the annotated
     * map. This will simply return the type that the map object is
     * composed to hold. This must be a serializable type, that is,
     * it must be a composite or supported primitive type.
     *
     * @return this returns the key object type for the map object
     */
    protected Type getKeyType() throws Exception {
        if (keyType == null) {
            keyType = label.keyType();

            if (keyType == void.class) {
                keyType = getDependent(0);
            }
        }
        return new ClassType(keyType);
    }

    /**
     * This is used to acquire the dependent value for the annotated
     * map. This will simply return the type that the map object is
     * composed to hold. This must be a serializable type, that is,
     * it must be a composite or supported primitive type.
     *
     * @return this returns the value object type for the map object
     */
    protected Type getValueType() throws Exception {
        if (valueType == null) {
            valueType = label.valueType();

            if (valueType == void.class) {
                valueType = getDependent(1);
            }
        }
        return new ClassType(valueType);
    }

    /**
     * Provides the dependent class for the map as taken from the
     * specified index. This allows the entry to fall back on generic
     * declarations of the map if no explicit dependent types are
     * given within the element map annotation.
     *
     * @param index this is the index to acquire the parameter from
     * @return this returns the generic type at the specified index
     */
    private Class getDependent(int index) throws Exception {
        Class[] list = contact.getDependents();

        if (list.length < index) {
            return Object.class;
        }
        if (list.length == 0) {
            return Object.class;
        }
        return list[index];
    }

    /**
     * This is used to provide a key XML element for each of the
     * keys within the map. This essentially wraps the entity to
     * be serialized such that there is an extra XML element present.
     * This can be used to override the default names of primitive
     * keys, however it can also be used to wrap composite keys.
     *
     * @return this returns the key XML element for each key
     */
    public String getKey() throws Exception {
        if (key == null) {
            return key;
        }
        if (isEmpty(key)) {
            key = null;
        }
        return key;
    }

    /**
     * This is used to provide a value XML element for each of the
     * values within the map. This essentially wraps the entity to
     * be serialized such that there is an extra XML element present.
     * This can be used to override the default names of primitive
     * values, however it can also be used to wrap composite values.
     *
     * @return this returns the value XML element for each value
     */
    public String getValue() throws Exception {
        if (value == null) {
            return value;
        }
        if (isEmpty(value)) {
            value = null;
        }
        return value;
    }

    /**
     * This is used to provide a the name of the entry XML element
     * that wraps the key and value elements. If specified the entry
     * value specified will be used instead of the default name of
     * the element. This is used to ensure the resulting XML is
     * configurable to the requirements of the generated XML.
     *
     * @return this returns the entry XML element for each entry
     */
    public String getEntry() throws Exception {
        if (entry == null) {
            return entry;
        }
        if (isEmpty(entry)) {
            entry = DEFAULT_NAME;
        }
        return entry;
    }

    /**
     * This method is used to determine if a root annotation value is
     * an empty value. Rather than determining if a string is empty
     * be comparing it to an empty string this method allows for the
     * value an empty string represents to be changed in future.
     *
     * @param value this is the value to determine if it is empty
     * @return true if the string value specified is an empty value
     */
    private boolean isEmpty(String value) {
        return value.length() == 0;
    }

    /**
     * This provides a textual representation of the annotated field
     * or method for the map. Providing a textual representation allows
     * exception messages to be reported with sufficient information.
     *
     * @return this returns the textual representation of the label
     */
    public String toString() {
        return String.format("%s on %s", label, contact);
    }
}
